textproduct: Rapid City

KEY MESSAGES

- Isolated to scattered severe thunderstorms possible again on Saturday with the highest risk across northwestern SD. Main hazards will be very large hail (1 3/4+" in diameter) and significant wind gusts (74+ mph). An isolated tornado can't be ruled out.

- Isolated severe storms possible on Sunday across much of northeastern WY into western SD.

- Near the middle of next week through the second week of July, temperatures will be well above normal. Confidence in daily high temperatures in the 90s to low 100s is increasing. The CPC has much of the CWA under a risk of extreme heat.

UPDATE

Issued at 920 PM MDT Fri Jun 26 2026

Thunderstorms made their presence known this evening across NE WY and W SD. Wind gusts have been around 50 to 65 mph but a few localized reports have been near 70 to 80 mph in the W SD plains. Hail reports have been mostly pea to dime sized but a couple storm cells were able to produce quarter sized hail stones. And heavy rain was also reported with widespread reports of quarter to half inch of rain. Thank you to everyone who sent in reports, they are greatly appreciated.

Looking ahead, these storms will continue to march eastward through the plains. The backside of these storms have light to moderate rain that will slowly diminish, leaving behind lingering clouds that will also diminish.

Saturday and Sunday are still looking hot with afternoon temps in the 80s to 90s, cooler 70s in the Black Hills. And it's still looking like strong to severe thunderstorms are a good possibility.

Latest hi-res models are still hinting at storm initiation in NE WY and SW MT around 2PM and those storms would track northeast into ND. As the low pressure center wraps up, another round of storm initiation is possible in W SD after 6PM. But the location of that second around is uncertain. Some models and model runs want to start the storms near the Black Hills while others start the storms farther east in the plains. It will be a battle of whether or not the cap holds. For sure worth being weather aware Saturday.

The stormy pattern continues into Sunday with a similar set up but shifted to the east a little bit, so storm initiation would be more likely in eastern Wyoming with storms tracking into South Dakota. Another day to be weather aware.

DISCUSSION

(This Evening Through Friday) Issued at 135 PM MDT Fri Jun 26 2026

Visible satellite shows cumulus struggling to develop over the Black Hills with midlevel clouds moving in from northeastern WY. Current mesoscale analysis shows nose of 500-1000 J/kg ML CAPE pushing into southwestern SD with 150-200 J/kg CIN. The 18z sounding from KUNR shows ~1000 J/kg SB CAPE with a strong cap. While short range model guidance shows increasing ML CAPE over western SD into northeastern WY through this afternoon with 1500- 2000 J/kg ML CAPE over much of western SD into portions of the Black Hills by later this afternoon into this evening, 500 mb height rises and warm 700 mb temps may limit convective development across much of our CWA. Most recent CAMs show convection developing over the higher terrain in WY and moving into northeastern WY by later this afternoon. Inverted-V profiles and low level curvature in forecast hodographs indicate a damaging wind and large hail threat. Storms will push east into western SD by this evening, moving out of the CWA by midnight.

Severe potential continues on Saturday as a shortwave and attendant lee sfc trof/low moves through the region. As the sfc trof deepens over western SD, axis of 2500-3000 J/kg ML CAPE will develop across much of the western SD plains and northwestern SD. The greater shear of 35-45KT will be displaced further west of the greatest instability, though there is some overlap over northwestern SD. Current CAMs show discrete storms firing over southeastern MT and moving into northwestern SD by Saturday evening. These storms will be capable of very large hail (greater than 1 3/4") and significant wind gusts (74+ mph). Tornado threat is low but not zero and an isolated tornado is certainly possible with any discrete supercells that form.

Unsettled southwest flow continues over the CWA through Sunday as the western US trof deepens. This will result in chances for storms (some may be strong to severe) later Sunday into Monday. Additionally, temperatures will continue to warm through this weekend with highs in the 80s to 90s by Saturday and Sunday. After a slight cool down on Monday, ensemble guidance is signaling much warmer weather with daily chances for isolated storms later in the week as a ridge builds to our east.

AVIATION

(For the 06Z TAFS Through 06Z Saturday Night) Issued At 1017 PM MDT Fri Jun 26 2026

Thunderstorms are moving east through central South Dakota. Some isolated and sporadic showers may pop up through the night in eastern South Dakota, but VFR conditions are expected for both sites. Winds will remin gusty through tonight and into Saturday afternoon.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.